The current interest in producing hard copies from electronically stored information by using electronic output to modulate exposure sources such as lasers, laser diodes and light emitting diodes (L.E.D.) has created a demand for infra-red sensitive recording materials. It has been known for many years that silver halide emulsions can be spectrally sensitised to the infrared by use of spectral sensitising dyes. There are numerous references to dye structures for sensitising dyes which are stated to include infra-red within their sensitising range. Examples of patents disclosing such dyes are listed in U.S. Pat. No. 4011083. Infra-red sensitising dyes are generally cyanines derived from quinoline-2, quinoline-4, naphthothiazole, benzothiazole or benzoselenazole.
A group of benzoxazole dyes has now been found to possess particularly favourable spectral sensitization properties in the infra-red.